<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
		 body{
			 height: 10000px;
		 }
		 #menu{
			 height: 140px;
			 background-color: bisque;
		 }
		 #nav{
			position: sticky;
			 height: 50px;
			 background-color: blue;
			 top: 10px;
			 width: 1000px;
		 }
		</style>
		 <script>
		  var str="Dog is a good dog";
		  var reg=/dog/ig;
		  str=str.replace(reg,"Cat");
		  alert(str);
		  var phone="abc13524331131ffff";
		  var reg2=/^\d{11}$/;
		  
		  alert(reg2.test(phone))
		 </script>
		 
	</head>
	<body>
		<div id="menu"></div>
		<div id="nav">搜素</div>
	</body>
</html>
